How to Catch a Giant Trevally on Fly (A Complete Guide)

A professional giant trevally fly fishing guide and saltwater fishing expert, shares with you the gear you need for GT Fly Fishing.

In this article, I’m going to share with you everything you need to know about how to catch giant trevally on fly.

I’ve fished and guided for giant trevally in many countries including Sudan, Seychelles, South Africa, and the Maldives. I’ve spent countless hours on the flats targeting these amazing fish.

Disclaimer: IntoFlyFishing.com is a participant in the Amazon Services LLC Associates Program, as an Amazon Associate I earn from qualifying purchases. Please see our Privacy Page for more information.

What Is a Giant Trevally?

If you’re reading this article, you’re most likely familiar with the species. But if you’re not, the giant trevally, or Caranx Ignoblis, is the largest of all the trevally species in the world. They inhabit the tropical waters of the Indian Ocean and the western parts of the Pacific.

a giant trevally underwater in the late evening

Giant trevally in excess of 50 kgs is not an uncommon capture by spin fisherman. They can even grow to weights in excess of 80 kgs, or 180 lbs. It’s just a badass predatory fish that eats anything from crabs to fish.

Don’t miss our full guide to Fly Fishing for Giant Trevally.

What Makes Giant Trevally So Special to Catch on Fly?

So, what makes GTs so special to catch on fly?

Giant trevally has become one of the icons of saltwater fly fishing, right up there next to tarpon, bonefish, and permit. They’re just amazingly beautiful, and apart from the fact that in order to target them you have to travel to remote and far-off locations, I think the main reason they’re such a cool target on the fly is how they eat a fly. 

When a giant trevally comes in at full speed, opens its mouth, and annihilates your fly, that image right there will keep replaying in your mind for years to come. I think that the speed and aggression these fish display is what makes anglers so addicted.

Pierre Joubert, the author, holding a large giant trevally he caught on a fly rod in the maldives. (Catch and release)

Once you hook into a decent specimen, you’ll soon realize that you’re not completely in control. It’s a humbling experience standing in the water with a powerful 12wt rig with a 120 lb leader and you can’t turn the fish.

GTs are dirty fighters. They play according to jail rules, and if you’re lucky enough to land one, you’ll know exactly what I mean when I say this is a special fish.

Watch How to Catch Giant Trevally on Fly Part 1 Video

Fly Fishing Gear for Giant Trevally

Before attempting to tackle these fish, it’s important to have the correct gear. I can’t emphasize this enough. Every single piece of gear needs to be of top quality and the strongest you can get. Giant trevally will test your gear to the absolute limit, and if there’s any weak spot it’ll break – guaranteed.

the author, Pierre Joubert, holding the fly rod he used to fish for GT in the maldives.

The Best Fly Rods for Giant Trevally

Let’s start with the rod.

I only recommend 12wt rods for GTs. Yes, you can catch small specimens up to 80 cm easily with a 10wt, as we did in the Maldives, but if you accidentally hook into a 90 cm plus fish, you’ll lose that fish.

Get a 12wt rod from a reputable manufacturer that has decent after-sales service. These trips are generally very heavy on gear, so there’s a good chance you’ll have to replace a section somewhere in the rod’s lifetime. Both the 12wt rods I took to the Maldives are still in for repairs.

Also, make sure that you take a spare rod with you.

Some of the best GT rods, which I have personal experience with, are:

The Best Fly Reels for Giant Trevally

On large fish, the reel’s drag is generally what helps to stop the fish. It needs to do so smoothly, and most importantly, with a lot of force. If you hook into a good GT around coral or in the surf zone, you need to stop it as soon as possible.

In terms of drag type, I wouldn’t say discs are better than cork or cork is better than discs. I will say that it’s important to buy a really decent reel, especially when buying one with a sealed drag.

Although most of the big 12wt reels carry more than 300 yards of backing, you rarely need it when fishing for GTs. If a 120 cm GT has taken 200 yards of backing, you’ve lost the fight. What you need to look at is how strong the drag is and the reputation of the reel.

Some of the best GT reels are:

Backing

The choice in backing is relatively simple, as the same rule applies to all the other gear used for GTs – get the strongest stuff. 80 lbs is what I use, and I’d say this is the minimum. Remember, the big thing here isn’t that you’ll apply 80 lbs of pressure on the fish, but rather to give you some leeway in case some of the strands get nicked by coral.

I use standard casting braids, like Powerpro or Berkley. Cortland’s 80 lb spliceable backing, which is hollow, is also a great option if you want to splice the fly line directly into the backing to create a very smooth connection.

  • Cortland Spliceable Hollow Core 80 lbs
  • Berkley ProSpec Chrome Premium Saltwater Braid 80 lbs
  • Berkley ProSpec Chrome Premium Hollow Braid 80 lbs
  • Powerpro Braid 80 lbs
  • Powerpro Hollow-Ace 80 lbs

Giant Trevally Fly Lines

The fly line industry has really come a long way to develop fly lines specifically for giant trevally. A couple of years ago, you’d have to make do with tarpon-orientated fly lines. These lines were ok to deliver flies, but not necessarily the best to fight giant trevally.

These days, most top fly line manufacturers produce giant trevally lines which integrate a much stronger core and have a taper to successfully deliver large flies. These lines include:

All of these are floating fly lines, which are perfect as you’re generally targeting these fish in shallow water or on the surface with poppers.

Also, don’t worry about the welded loops on a line or choose a line above another because it has welded loops. These will be replaced with a more durable option.

Leaders for Giant Trevally

In most cases, you’ll want to fish with monofilament or fluorocarbon leader material with a breaking strain between 100 and 120 lbs. If you do fish on a white sand flat scenario or keep getting refusals, drop down to 80 lb fluorocarbon – but just keep this in mind when you’re fighting the fish.

The length of the leader will be around 9 ft and should be refreshed each day or if you feel that it’s nicked. Even a little bit of abrasion weakens the leader, so make sure to replace it frequently.

Some of the best leader materials I’ve come across are:

  • Cortland Fluorocarbon 60-80 lbs
  • Cortland Monofilament 100 lbs
  • Seaguar Blue Label 60-80 lbs
  • Sufix Zippy 100-120 lbs

Connections

There are many ways to make solid connections from the backing to the fly line and fly line to leader. I won’t go through all of them and will just share what I use.

This method is what we mostly used as guides in Seychelles, and I’ve not seen any of them slip or break. The downside is that it’s relatively bulky, but once you learn to manage it, you can fish with confidence.

Backing Connection

My favorite backing knot for giant trevally is a double Bimini twist. I use the double version as it increases the surface area that connects to the fly line. Thus the pressure is distributed over a larger area. The key here is to make sure that the loop you create is big enough for a fly reel or fly line spool to pass through. This will enable you to change fly lines on the go.

Front and Back Fly Line Connection

Now to the fly line connection. The first thing to do is snip off any existing welded loop. I’ve seen these pop in the past, and even though it’s heartbreaking to cut a brand new fly line, it’s nothing compared to seeing your dream fish swim off with your chartreuse Semper in the corner of its mouth – been there, done that, got the emotional scar.

I replace the front and back loop with a connection where you thread the line through a hollow braided material. You then double it over and secure it with three nail knots.

Knots for Giant Trevally

When choosing a knot to use on your leader material for giant trevally, to either connect it to the fly line or tie a fly on, you should keep a couple of things in mind. The first is that the leader material is very stiff.

the author, Pierre Joubert, explaining the different knots needed for GT and the importance of good knots

The flies must have as much life as possible, and if you tie a knot right up against the eye of the hook, the fly will be lifeless. For this reason, all knots are loop-styled knots.

The stiff leader material influences how the fly sits and swims in the water. Some loop knots result in a slight angle, which is fine if you fish a 20 lb leader, but if you fish 100 lbs it drastically impacts how the fly swims.

It goes without saying that the knot should be as strong as possible.

Some of my favorite knots for GTs are the Reverse Homer Rhodes and the Perfection Loop. I use the Reverse Homer Rhodes when I have time to tie it, but when things happen fast it’s hard to beat a Perfection Loop.

Giant Trevally Flies

Now which flies should you consider when targeting giant trevally? Although these fish are notoriously aggressive and eat anything, they can be surprisingly picky. Therefore, a good selection of flies is absolutely necessary.

one of the team anglers holding up a crab variation fly, one of the best flies used for targeting GT on fly.

Let’s look at some of the best giant trevally patterns and why they work so well.

Semper

The Semper is my go-to GT fly and is the first fly that I’ll tie on in almost any GT fishing scenario. In its original form, it’s tied using only natural materials, which include bucktail and schlappen for the tail and a ton of marabou for the body and head of the fly. Depending on the color combination of the fly, a Semper can resemble many different aquatic lifeforms including baitfish, squid, and large shrimp.

Some of my favorite color combinations include:

  • Tan and white
  • Olive, black, and red
  • Chartreuse and white (This combination worked exceptionally well on our recent Maldives trip.)
  • Black and purple

Clouser Minnow

The Clouser Minnow needs no introduction as a great saltwater fly, but many anglers, for some reason, don’t see it as a legitimate giant trevally fly. From my experience, the Clouser Minnow produces fish in scenarios where the other patterns fail. This is especially true in areas where the fish see a lot of flies or keep refusing your more traditional GT flies.

The key here is to tie giant trevally Clouser Minnows on good hooks. My favorite hook for this application is the Gamakatsu SC15-2H in a 5/0. I only carry three color combinations in my box, which are:

  • Tan over white
  • Olive over white
  • Chartreuse over white

Large Merkin

Another unorthodox giant trevally fly pattern is the Merkin. Permit anglers around the world know this pattern well, and I can assure you that with some minor tweaks, the Merkin is a great GT fly. The first tweak is the hook, which needs to be upped considerably. Here I go for a Gamakatsy SL12 6/0 oR the SC15-2H 5/0. Because the Merkin is tied on a bigger hook, the overall size must be increased too.

This isn’t necessarily a GT fly I’ll put on from the get-go, but it’s a good option to have when the GTs are on the flats. I’ve seen schools of GTs tail just like permit or bonefish in thick turtle grass, and in this scenario the large Merkin works incredibly well. Match the color to the bottom and stick to natural color combinations. 

EP Baitfish

The EP Baitfish pattern is tied entirely out of synthetic fibers. This is the main reason for its success, as once the caster gives a back cast, the fly disposes of all the water that was absorbed when the fly was in the water. It’s this characteristic that makes an EP Baitfish so easy to cast and allows it to land softly. 

The EP Baitfish works well on very calm days when the fish are easily spooked, as you can deliver the fly closer to them. Good color combinations include:

  • Black over purple or blue
  • Tan over white
  • Chartreuse over white
  • Red

Double Barrel Popper

If you’re working deeper water or pulling a fly over a fast-moving channel, you need a fly that makes a huge commotion. You need a Double Barrel Popper. The Double Barrel Popper makes use of a huge foam popper head and a long lifelike tail. The fly is tied on large hooks (8/0 instead of 6/0) to open the hook gape up to ensure better hookups.

The Double Barrel Popper is not necessarily the easiest fly to cast in the world, and working it quickly and repeatedly through a channel takes a lot of energy. But, when you see a big GT hammer the popper out of nowhere, you’ll forget all about the pain.

Where to Catch Giant Trevally on Fly

Giant trevally is generally a reef species, so they congregate around reef structures where they’re on the lookout for prey. Here are three typical locations where you can target GTs on fly.

watching the plane leave in the maldives

Sand or Coral Flats

When the tide pushes and the water becomes deep enough to swim in, GTs are often found on flats. I’ve seen them on any kind of flat including coral, turtle grass, and even white sand flats.

Surf

Probably one of the best places to catch GTs is in the surf zone, especially when the tide is pushing from low to high. The rougher the conditions and the bigger the sea, the more these fish seem to like it.

On the downside, it’s also the hardest place to catch GTs, as standing in the surf and casting at these fish is physically exhausting. The ground on which you’re standing is mostly uneven and made of incredibly sharp coral.

I think what makes the surf zone such an effective spot to catch GTs is that they know they don’t have a lot of time to make a choice, almost like trout in a very fast run. They have to come in with the wave, eat whatever they can, and get out again without running out of water.

Deeper Water

In deeper water, you’ll have to target GTs from a boat or skiff. This adds so much flexibility to your day, as you’re able to go to deep water reefs when the fishing has switched off on the flats.

Here you either dredge with a sinking line and heavy fly or you try to call the GTs up with a big popper. The fishing can be extremely exhilarating as you sometimes have a couple of GTs hitting your fly at once, but it’s very tiring. You often spend hours casting a 12wt rod before finding fish.

The Best Giant Trevally Destinations

Let’s look at some of the best destinations to catch giant trevally on fly.

Seychelles

I have an incredible love for Seychelles and especially its outer atolls where I guided for these incredible fish. In my opinion, these outer atolls of Seychelles offer the best giant trevally fishing there is, hands down. The best atolls are:

  • Cosmoledo
  • St. Francois
  • Astove
  • Farquhar

Red Sea

If you’re looking for a very unique but incredibly hard fishing experience, the Red Sea offers amazing giant trevally fishing. From a fly fishing point of view, the Red Sea is probably best known for its astounding numbers of triggerfish (it’s the triggerfish capital of the world), but there’s always a chance of hooking up to a serious GT. 

Maldives

The Maldives offers a more affordable and comfortable fishing experience, and after our recent trip there, I must admit I was blown away by the number of giant trevally we saw. This is a seriously underrated fishery at the moment, and if you put the time and effort in to get to the best spots, you’ll be richly rewarded.

Casting for Giant Trevally

Let’s talk about casting for giant trevally. Delivering the fly to the fish is no different than to other predatory fish species, but because you’re fishing with a 12wt rod and because things tend to happen very fast, you need to be aware of a couple of things.

Your guide can put you in the most incredible situation with GTs feeding all around you, but if you can’t deliver the fly in the right spot, you won’t catch a fish. It’s as simple as that.

casting for giant trevally with a fly rod in the maldives

The first and most important thing is to practice. And I don’t mean take your rod to the park once and swing it around a bit. Nope, that won’t cut it. My first recommendation is to book a good number of sessions with a casting instructor that has fished for GTs before.

Then, you need to go and practice casting that rod as much as you can. Cast far, cast short, cast accurate, cast in the wind, and cast with as few false casts as possible.

Ask any GT guide in the world what the one thing they wish their clients could do better, and the answer from all of them will be casting. Prepare your casting well, and you’ll be able to make the most of your shots.

Contrary to what all the GT videos are showing, and even our videos are guilty of this, is that it’s not full-blown action all of the time. We spent countless hours casting and looking for GTs without getting anything. Then, out of nowhere, it just switches on for a brief moment. You need to be prepared and well practiced.

The other comment on casting is to not underestimate how far you can lead these fish. If you drop the fly on a GTs head, they’ll spook 90% of the time. They’re not used to a fish flying through the air towards them.

Giant trevally are designed to spot prey and hunt them down, so give them something to work for. Lead the fish well and pick up the retrieval rate as the fish shows interest.

Fighting Giant Trevally

Before casting to a GT, it’s important to set the drag of your reel to the desired setting, which in most cases is turned to the max. This maximum drag will stop smaller fish and, if all your connections and the hookup are solid enough, large fish will still be able to run a bit.

the guys casting for GT in the maldives

The fight itself will depend on the individual hooked and in what type of water they’re hooked.

Small GTs (Under 85 cm)

Small GTs are such a blast to catch, and they pull hard. However, these fish are no match for the caliber of gear we use for larger GTs. With these fish, you can apply maximum pressure without giving them an inch of line.

Because of this, the fight is generally very short and the fish swim away with a good and healthy kick on the release.

Large GTs (Over 85 cm)

These fish are what the entire game is about (especially fish over the prized 100 cm mark). Large GTs fight considerably harder and, once hooked, you’ll realize you’re not in control and you won’t be able to stop them.

If you’re on a skiff, you’re in luck, as you can follow the fish and try to remove the fly line from all the coral heads and other snags. On foot, it’s another game. Here you’re holding on for dear life during the first run. If you can make it through the first run and the fish hasn’t wrapped you around coral heads, you’re in with a good chance.

Keep the rod angle low and apply as much pressure on the fish as possible.

Landing and Handling Giant Trevally

Giant trevally have incredibly sharp scutes in front of their tail fin. This is the exact area where you need to grip the fish when landing it, so be sure to wear a thick pair of gloves.

Once you grip the tail, be sure to do so very securely and be ready for serious tail shakes. On big specimens, you’ll have to use both your hands.

a beautiful day for fly fishing in the maldives. Angler casts line on salt flats

One of the things that has always blown my mind about these fish is how calm they are after you’ve landed them. As soon as you have the fish by the tail, keep its head in the water at all times and kneel down next to it.

Hold the fish in front of the tail fin with one hand and place your other hand under the hard surface just behind its gill plate. Get a couple of quick photos while always keeping the fish wet, remove the fly, and send her off on her way.

Conclusion

I hope that you found this article on how to catch giant trevally on fly helpful. They’re really one of the most spectacular fish species. Nothing I can say will ever be able to prepare you for the entire experience of catching them. It’s something you need to experience for yourself.

Just be careful, once this bug has bitten there’s not a lot else out there that gets even close.

If you have any more questions on targeting GTs on fly, or would like to find out more about our trip and would like to join us for our next one, please leave your questions in the comment section below.

Until next time.

SHARE THIS POST

Disclaimer: IntoFlyFishing.com is a participant in the Amazon Services LLC Associates Program, as an Amazon Associate I earn from qualifying purchases. Please see our Privacy Page for more information.

Pierre is a fly fishing guide and professional photographer who has guided and hosted trips for top fly fishing outfitters. Since being introduced to fly fishing over 21 years ago, he has travelled, fished and guided across the globe. He has extensive knowledge on specific gear and tackle selection for various salt- and freshwater species. Some of his writing work includes blogposts for Alphonse Fishing Company and African Waters.

You may also like...

A speckled trout in a river rests on top of a stone.
Read this article before you go fishing for speckled trout. It'll teach you what you need to know about their diets and feeding habits.
Sea bass fish under deep blue sea water.
Read this article about sea bass feeding habits before you fish for them. It gives you plenty of information on their aggressive tendencies.
A trophy ten pound largemouth bass caught on plastic worm.
Read this article if you're interested in learning about the feeding habits and preferences of Largemouth Bass.